Detecting Effects of Filaments on Galaxy Properties in the Sloan Digital Sky Survey III

TL;DR

This study investigates how galaxy properties in SDSS are influenced by their proximity to cosmic filaments, revealing significant correlations that support filaments as key tracers of galaxy environment effects.

Contribution

It provides empirical evidence linking galaxy properties to filament proximity using SDSS data and the Cosmic Web Reconstruction catalogue, extending understanding of environmental influences.

Findings

Red and high-mass galaxies are closer to filaments than blue and low-mass galaxies.

Galaxy properties like stellar mass and size are significantly affected by filament proximity up to z=0.7.

Filament effects are comparable to those observed with galaxy clusters as environmental tracers.

Abstract

We study the effects of filaments on galaxy properties in the Sloan Digital Sky Survey (SDSS) Data Release 12 using filaments from the `Cosmic Web Reconstruction' catalogue (Chen et al. 2016), a publicly available filament catalogue for SDSS. Since filaments are tracers of medium-to-high density regions, we expect that galaxy properties associated with the environment are dependent on the distance to the nearest filament. Our analysis demonstrates that a red galaxy or a high-mass galaxy tend to reside closer to filaments than a blue or low-mass galaxy. After adjusting the effect from stellar mass, on average, early-forming galaxies or large galaxies have a shorter distance to filaments than late-forming galaxies or small galaxies. For the Main galaxy sample (MGS), all signals are very significant ($>6\sigma$). For the LOWZ and CMASS sample, the stellar mass and size are significant ($>2 \sigma$). The filament effects we observe persist until $z = 0.7$ (the edge of the CMASS sample). Comparing our results to those using the galaxy distances from redMaPPer galaxy clusters as a reference, we find a similar result between filaments and clusters. Moreover, we find that the effect of clusters on the stellar mass of nearby galaxies depends on the galaxy's filamentary environment. Our findings illustrate the strong correlation of galaxy properties with proximity to density ridges, strongly supporting the claim that density ridges are good tracers of filaments.